DESC: The 180mm Maksutov-Cassegrain optical system has greater light grasp than a 150mm Mak, you'll get brighter images and better resolution. No other optical design can deliver such potent optical specifications in a package.The meniscus lens is fully multicoated for maximum light transmission, further enhancing image brightness. The dovetail rail on the underside of the tube attaches to your Orion SkyView Pro, Sirius, or Atlas mount.